1. Field of the Invention
The present invention relates to a light shielding unit which controls illumination light (illumination light beam), a variable slit apparatus which forms the shape of the illumination light into a slit shape, etc., an exposure technique using the variable slit apparatus, and a technique for producing a device using the exposure technique.
2. Description of the Related Art
For example, upon producing a semiconductor device or the like, in order that a pattern, which is formed on a reticle (or a photomask or the like), is transferred onto a wafer (or a glass plate or the like) coated with a resist to perform the exposure, an exposure apparatus has been hitherto used, which employs, as the exposure light (exposure light beam), a light (light beam) in the range from the far ultraviolet region to the vacuum ultraviolet region including the emission line of a mercury lamp, the excimer laser beam, etc. Recently, in order to enhance the resolution by shortening the exposure wavelength, an exposure apparatus (hereinafter referred to as “EUV exposure apparatus”) has been also developed, which employs, as the exposure light, the extreme ultraviolet light (hereinafter referred to as “EUV light”) which has a wavelength of, for example, not more than about 100 nm.
In relation to the exposure apparatuses as described above, in a scanning type exposure apparatus (for example, a scanning stepper) in which the wafer is exposed while synchronously moving the reticle and the wafer with respect to the projection optical system, the illumination area, with which the reticle is illuminated, is defined to have a slit shape such as a rectangular shape or a circular arc shape, etc. which is long in a direction perpendicular to the scanning direction. Conventionally, in order to define the slit-shaped illumination area, for example, a variable blind is used, which is provided with a first blind having a plurality of movable blades for defining the shape of a long side of the illumination area and a second blind having, for example, a substantially linear or circular arc-shaped edge portion for defining the shape of the other portion of the illumination area other than the long side (see, for example, International Publication No. 2005/48326).